1. Field of the Invention
The present invention relates to a flyback transformer for use in an electronic apparatus such as a television receiver and the like.
2. Description of the Prior Art
In a conventional flyback transformer, a low tension coil bobbin has been employed with an insulating construction as shown in FIGS. 1 to 3 for winding both a primary coil 1 and tertiary coil 2 thereon. The low tension coil bobbin 3 provides an upper cylindrical hollow portion 4 for the primary coil 1, a lower cylindrical hollow portion 5 for the tertiary coil 2, and a terminal board 6 providing a plurality of connecting terminals 7. The primary coil 1 is wound on the upper hollow portion 4, the terminal ends of which being drawn out from the upper hollow portion 4 to the terminal board 6 through the lower hollow portion 5 to be connected with the connecting terminals 7, while the tertiary coil 2 is wound on the lower hollow portion 5 through a sheet or tape 8 of insulating materials such as Mylar tape (Mylar is a trade name owned by E. I. du Pont de Nemours & Co., Inc. of the U.S.A.) to be provided between the tertiary coil 2 and the terminal end of the primary coil 1 drawn out from the upper hollow portion 4 to the terminal board 6, as shown in FIG. 3, the terminal ends of the tertiary coil 2 being drawn out from the lower hollow portion 5 to the terminal board 6 to be connected with the connecting terminals 7. It is to be noted that not only the application of the Mylar tape on the terminal end of the primary coil 1 is a kind of work inducing trouble such as mislocations of the tape 8, taking a lot of time for putting the tape 8 in the right position, but also the property of the Mylar tape is not absolutely enough for the insulation between the primary coil 1 and tertiary coil 2 in the case of that the flyback transformer is used as an electronic apparatus under various circumstances. If there suddenly occurs a short-circuit between the primary and tertiary coils 1 and 2 of the flyback transformer used in the electronic apparatus, the apparatus is rendered less safe for the operator because the power source connected to the primary coil 1 is directly connected to signal lines connected to the tertiary coil 2 such as a video terminal, RGB terminal or the like which lead outside from the cabinet of the apparatus. Therefore, in the field of electronic apparatuses, it is desired to provide a flyback transformer of a type in which the tertiary coil 2 is completely insulated from the primary coil 1 in order to prevent from making trouble of short-circuit therebetween in any situation of the transformer.